What is lurking in your pool?

PhD student investigates what all those chemicals could be doing to swimmers

Engineering PhD student Roberta Dyck is a woman with a mission—making swimming pools safe for all from the dreadful-sounding disinfection by-products (DBPs).

“All water—including drinking water—has naturally occurring organic materials, which can originate from leaves and other vegetation, that react with chlorine to produces chemicals called DBPs,” explains Dyck. DBPs in drinking water have been associated with health risks such as cancer and reproductive disorders.

“This is why Health Canada has established guidelines for DBPs in our drinking water that aim to minimize any potential adverse health effects,” she says. “But in most countries we don’t have similar regulations in place for swimming pools, where chlorine is not only reacting with the naturally occurring material resulting from source water, but also with what swimmers bring into the pool with them—sweat, urine, perfumes, hairspray, deodorant and skin excretions, to name a few.”

Dyck has developed a way to estimate the total exposure of DBPs—specifically trihalomethanes (THMs)—in both the air and water for swimmers and people who work at the pool.

The model was developed using data previously collected from samples taken from 15 different swimming pools in Quebec City by researchers at Laval University, as well as data—air and water concentrations for five pools in Italy—provided by Italian researchers.

The model examines the process and rate THMs enter the human body—dermal absorption, ingestion and inhalation—for five different age groups and estimates total exposure for individuals, taking into account a range of concentrations and other variables.

For example, the model could estimate the total annual or lifetime exposure of THMs for a three-year-old child, weighing 35 lbs, who swims twice a week for one hour a day.

One of the most significant findings, says Dyck, was that for total exposure, children aged 1-4 have up to six times the exposure of other age groups. The results of this research have been published in the journal Water Research.

“Many swimmers using indoor public pools are children, pregnant women and seniors, who may be at greater risk for health effects from chemical exposures in swimming pool water; therefore, it is important to quantify the associated exposure and risk,” says Dyck.

“In the future, the model will allow us to perform a health risk assessment and develop strategies that minimize DBP exposure without compromising disinfection efficiency. It’s important to remember that chlorination is necessary to protect swimmers from pathogens in the water. But we also need to better understand the effects, and how to manage them.”

Some risk management strategies could include the development of health-based guidelines for disinfection practices and policies, as well as optimizing the design of ventilation and filtration systems for swimming pools.

With the model validation complete, Dyck is now looking at what happens to DBPs once they enter into the human body.

Dyck’s research is funded by NSERC, and supported by Rehan Sadiq, associate professor of engineering at UBC’s Okanagan campus and Manuel Rodriguez from Université Laval. The research is an international collaboration with contributions from Guglielmina Fantuzzi, Elena Righi and Gabriella Aggazzotti from the University of Modena, Italy, and Robert Tardif from the University of Montreal.